Annual amount spent by U.S. individuals, companies, and government agencies on foreign-made products,
minus the amount spent by foreign entities on U.S.-made products;
accounting for about negative 2% of the GDP.
Note the "negative" in the last line: by definition, the trade deficit is subtracted as an adjustment factor.
That's because the other three factors in GDP measure "products made anywhere, bought by Americans";
by subtracting the trade deficit you're left with "products made in the U.S., bought by anybody".
See the interactive GDP Diagram.